And it's not like Europe isn't fighting back. European intelligence has been deep inside Russian networks since before the first invasion of Ukraine. From the European side, the invasion of Ukraine is a proxy war, with billions of euros spent on fighting Russia, while to Russia the war is a normal invasion with Russian (and now North Korean) troops on the ground.
The way Europe (except for Ukraine, of course) is fighting Russia mostly benefits Europe, as far as I can tell. Most of Europe's losses, so far, have been economical. Switching to a war economy to defend against Russia would probably cost more and be less effective. Until Ukraine falls, I don't see why Europe would want to change that deal.